Variable resistance



May 8, 1951 A R. G. FERRls E'rAL 2,552,482

VARIABLE RESISTANCE:

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Patented May 8, 1951 'VARIABLE RESISTANCE Robert G. Ferris, Harvard, Ill., and `lames D. Jordan, Washington, D. C., assignors to the United States of America as represented by the Secretary of the Navy Application June 24, 1944, Serial No. 541,990

8 Claims. l

This invention relates generally to variable resistors, and particularly to an improved resistor construction for controlling the operation and response of electrical components mounted in a projectile, such as `are provided; in certain types of fuzes.

One of the objects of the invention is to provide a variable resistor wherein the resistor element employed is completely coated with a protecting .compound so that corrosion cannot occur during storage.

Another object of the invention is to provide a variable resistor having a contacter element which normally does not engage the resistance element, but which penetrates the protective coating to engage said resistance element and establish an electric circuit automatically upon the occurrence of setback when the projectile is red.

Another object is to provide such a resistor which is easily adjustable from outside the projectile, is adapted to be used in controlling the action of a fuze, and is adjustable by turning a nose ring provided on the projectile in the usualY manner, so that an electrical fuze equipped with the'improved resistor may be adjusted by conventional fuze setting devices now in use.

A related object is to provide adjustable resistance means having the advantages last above outlined when employed in the controlling of a projectile fuze and which in addition, when so employed, constitutes a safety device maintaining the fuze in unarmed condition until the instant of firing.

StillV further objects of the invention will appear as the description proceeds.

In the drawings: v Fig. 1 is a longitudinal sectional view of a projectile nose fuze incorporating a resistor constructed in accordance with this invention, certain of the fuze parts being illustrated only diagrammatically, and adjacent parts of a projectile to which the assembly is secured being also fragmentarily shown;

Fig. 2 is a side elevational View of the setting or adjusting ring;

Fig. 3 is a sectional View taken substantially onA 'in the direction of the arrows, showing on a larger scale the principal parts of the variable resistor construction Fig. 6 is a sectional detail upon a scale still larger than that of Fig. 5, showing the positions taken by the set-back-operable parts after ring; and t (Cl. IGZ-70.2)

Fig. 7 is a detail sectional view taken substantially on the line E-l of Fig. 6, and looking in the direction of the arrows.

In the drawings similar numerals of `reference will indicate like parts throughout the views.

The numeral I indicates generally a projectile the details of construction of which form no part of the present invention, but which is illustrated as formed with an internally threaded open forward en-d 2. Screwed in the open end and extending into the projectile is a can 3 having a flange mouth 4 overlying and forming a continuation of the forward end of the projectile I. The mouth of the can is also counterbored or enlarged as at 5 to ,define a shoulder 6. Fitted in .the can 3 is a receptacle 'l ilared at its upper end at 8, to seat upon the shoulder 6. Through such flared or flanged portion 8 extend pins 9 for locking the receptacle in place.

Also tted in the counterbored portion 5 is an adjusting ring I8 having an enlarged forward portion tapered ccnformably to the other parts and forming a further forward continuation of the fuze assembly. The adjusting ring is rotatably retained by a snap ring i9. The snap ring is accessible through a plurality of plugged openings ISa which permit compression of the snap ring and removal of the adjusting ring at will. l

' The fuze body i2 projects through the adjusting ring I8 and into the receptacle 'I and is held in place by a snap ring I I. A pin 2'! in receptacle 'I projects into a slot 28 in the iuze body to lock the latter against rotating with the adjusting ring. The fuze body is provide-d with annular grooves near its midportion and underlying the adjusting ring, in which grooves the rings I3 and I4 are fitted. Ring I3 will hereinafter be identilied as the resistance ring, or element, and may comprise a conventional coated or wire wound resistor, being shown as of the coatedA type. Over the resistance coating the element I3 is covered with lacquer to protect its surface from corrosive action. The ring I4, which will hereinafter be identied as the conductor ring, is also coated with lacquer or the like to protect its surface.

The forward section I5 is formed separately from the body section I2 and held thereto by a split ring I6.

The adjusting ring I8 is provided with a recess 2| which confronts the rings i3 and I4. Mounted in recess 2| are disks 22m, 22h, 23. Inner disk 23 constitutes a Contact disk and is provided with a knur-led or sharply serrated inner surface 24 which bridges and bears against the lacquered surfaces of rings i3, I4, the lacquered coatings normally preventing the establishment of an electrical connection between theY rings by disk 23. Disks 22a and 22blconstitute backing disks and are formed of plastic material. The disk 22h is peripherally anged or cupped at 22e to receive and position the conta-ct disk 23, and complementary opposed groovesl 22d, 22e are. formed in disks 22a, 22D dening a passage, a continuation of which extends forwardly in ring i8. The entire passage thus formed is lled with lead, as indicated at 25.

In operation the resistance element i3. may be connected in an electric circuit with other components of a fuze designed for electrical operation in any desired manner. For example, the element i3 could be connected in a circuit in such manner that differences in the effective Value of the portion of resistance ring in circuit would have the effect of changing the timing of the fuze, or the intensity of the inuence required to detonate the fuze.

Fixed lugs, lll, 29, are provided, projecting rigidly from the xed front flange d ofthe can and from the adjusting ring I8, respectively, to facilitate adjustment of the latter, and these lugs are so arranged as to permit adjustment of the ring I8 by any of the standard fuze setting means now in use for projectiles of similar class. The setting of the ring i3 may be calibrated in any suitable manner. It will be understood, however, that prior to ring of the projectile, the disk 23 is insulated from the ring I 3 by the coating of lacquer. However, upon the occurrence of setiback, when the projectile is fired, thelead 25 will be driven rearwardly by the force of setback, separating the disks 22a and. 22o and driving disk 23 inwardly to force its knurled surface through the lacquer and into electrical contact with rings I3 and Ill.

We claim:

1. In a fuze construction adapted at leastpartially for electrical operation, an electrical resistance element, an insulating and protective coating over said resistance element, a contact element adapted to engage the resistance element at any of a plurality of points to provide a selected electrical resistance but normally held from engagement with said resistance element by said coating, and means including a relatively massive portion actuable by its inertia upon rapid acceleration of the projectile to fracture said coating and permit contact betweenl said contact element and resistance element.

2. In a f-uze construction adapted at least partially for electrical operation, a nose assembly axis of said nose assembly and including a relatively sharpV part electrically engagealole with said resistance element at any of a plurality o positions to provide a selected electrical resistance, an insulating and protective coating over said, resistance element and normally preventing effective engagement between said contact element and resistance element7 and means including a relativelj1 massive portion actuableby setback to force said contact element through said coating and into electrical connection with said resistance element.

3. In a fuze construction adapted at least partially for electricalv operation, a nose assembly including a body portion, an annular; electrical resistance element coaxially carried by said body portion, a contact element having a relatively sharp portion rotatable around the axis of said body portion and electrically' engageable with said resistance element at any of a plurality of positions to provide a selected electrical resistance, an insulating and protective coating over said resistance element and' normally preventing effective engagement between said contact element and resistance element, means for rotating said contact element including a ring accessible from the exterior of the nose assembly, and setback operable means for forcing said sharp portion of the contact element through said coating and into electricaly contact with said resistance element.

4. In a projectile fuze construction adapted at least partially for electrical operation, a nose assemblyv including a body portion, an electrical resistance element means including a movable contact for varying the effective portionof said resistance element,A an insulating coating preventing electrical' connection between said contact and` resistance element, and. setback operable means for drivingsaid contact throughY said.

coating to establish electrical connection between the contact and resistance.

5. A projectile fuze construction as dened. in.

claim 4 in which said setback-operable, meansv comprises a metallic mass capable ofl plastic deformation at ordinary temperatures and positioned to be urged against said contact by setback.

6. A projectile fuze construction as. dened in claim 4 in which said Contact ismovable in, one.

direction to vary the value of the resistance.

adapted to become effective upon penetration of' said' coating, and movable in another direction to penetrate the coating.

7,. A projectile fuze construction as denecl' in claim 4 in which said, contactY is movable inf. one direction to vary the value of theY resistance adapted to become` effective uponV penetrationt of.'

said coating, and movable in another direction.

to penetrate the coating, said, setback-operable means comprising a, mass of relatively heavy material adapted` to bear against the. contactv tov urge it in the first-mentioned direction upon setback.

8`. A projectile construction as defined in claim 4 in which said contact is movable in one direction to vary the value of the resistance adapted to become effective upon. penetration: of saidcoating, and movable in another direction4V to.

penetrate the coating, said setback-operable means comprising a mass of metal capableof.

plastic deformation at ordinary temperaturesbxr the force developedV in,v setback and trappedr in and' lling. a chamberY communicating with. saidcontact, a substantialv proportion of. sa-id. meta-l1 extending forwardly in. the direction of intended` REFERENCES CITED The following references are of record. in the filo ofv this patent:

UNITED STATES PATENTS Number Name Date'` 341,536 Zalinski May 1-1Jv 1886 FOREIGN PATENTS' Number Country Date 6340 Great Britain May 11, 1'886. of 1886 

